St John is being forced to re-shuffle its ambulance resources in an attempt to shoulder ballooning demand and a multimillion-dollar funding shortfalls.

Over the past five years, its annual operating loss has nearly doubled to $14 million, while its emergency call-outs have climbed more than 12 per cent - to a record 388,446 last year.

New Zealand's ageing population, a growth in chronic diseases and the rising costs of running ambulances will continue to stretch St John resources and push it further into the red.

Sweeping changes are being rolled out across the organisation to mitigate the pressure.

Under the changes, minor 111 calls, including headaches, pains and allergies, will likely be responded to with one paramedic in a car rather than a double-crewed ambulance.

Demand profiling for each call will determine how many paramedics are required to attend an incident and whether an ambulance, rapid response vehicle or single-crewed car would be most appropriate, St John Canterbury district operations manager Pete Cain said.

"We have got to take the resources we have and make them work better and more effectively. The onus is on us to do this."

St John receives 80 per cent of its funding from the Ministry of Health and the Accident Compensation Corporation (ACC). The remaining 20 per cent is met through commercial ventures, such as first aid training courses, but mostly by fundraising.

This year, the organisation had a fundraising shortfall of $30m.

The biggest loss to St John stems from its ambulance service. It costs about $1m a year to fund a double-crewed ambulance, Mr Cain said. "Over the years our job has changed. We used to be only for high acuity and traumatic injuries, but now people phone 111 because they know they will always be able to talk to someone and get a response. We have to reconfigure our services to meet that demand."

St John is shifting its focus from solely emergency response to also offering in-home based care and working alongside primary health organisations, he said.

Wellington Free Ambulance chief executive Diana Crossan said it was already piloting a similar tailored service on the Kapiti Coast. It would continue to operate full emergency ambulance services but it was also looking to offer in-home care.

Callouts and costs were rising each year. "We're going to need more and to do things differently in the future."

She said it cost about $21m a year to operate the ambulance service in the greater Wellington area. Of this $16-17m came from ACC, the Ministry of Health and the District Health Board and the balance from donations. Fairfax NZ